But after successful convictions in a
number of cold cases, around 2006 detectives realised that starting
from the beginning could yield results.

Edward Jarman, a forensic scientist who
specialises in body fluid analysis, carried out testing for blood,
saliva and DNA on items of clothing seized from the suspects' homes.

In the debris from the original evidence bag holding Gary Dobson's jacket, the team found three blood fragments which had less than a one in a billion chance of not being Stephen Lawrence's.

Another
blood fragment which had encased three fibres and matched Mr Lawrence's
DNA to the same probability was also discovered, although only a
partial profile for DNA testing was obtained.

Evidence: An LA Raiders jacket worn by Stephen Lawrence on the night he was killed. Fibres from his clothes were transferred to Gary Dobson's outfits. Two quite acrylic fibres from this jacket were found

Crucial: Four rare red-orange polyester fibres and seven quite common pink-orange fibres that matched Mr Lawrence's T-shirt (pictured above) - one of which appeared to be bloodstained

Bloody: A blue cardigan worn by the victim

When Dobson's jacket was examined all
over with a low-powered microscope, a tiny bloodstain measuring 0.25mm
by 0.5mm was found on the collar. This matched Mr Lawrence's DNA profile
to the same probability.

HOW DAMILOLA TAYLOR COLD CASE SUCCESS SPARKED NEW SEARCH

Success in cold cases including the death of Damilola Taylor sparked a new review which uncovered key forensic evidence in the Stephen Lawrence investigation.

A team of scientists at a private company called LGC were asked to ‘start again from scratch’ in working to uncover evidence against whoever killed Mr Lawrence.

Gary Pugh, Director of Forensic Services for the Metropolitan Police, said: ‘The Damilola Taylor case...involved what LGC have done in going right back to basics and starting from scratch.

'Many of these cases have had reviews over time but quite often they're with a presumption that if nothing's been found the items aren't re-examined.

‘What I think we've done here and in previous cases is start again from scratch and that was the brief we gave LGC in this particular case.’

The case of ten-year-old Damilola Taylor, who bled to death after an attack in 2007, involved the key discovery of a blood stain on the shoe of one of the defendants.

The defence argued that the stain had
been caused by saliva testing, however Mr Jarman found that when old
flakes of Mr Lawrence's blood were exposed to a chemical used in the
testing they became 'gel-like'.

They did not cause staining and would not absorb into the fabric.

He maintained that the most likely
cause of the stain was 'primary transfer', meaning that it was caused by
wet blood shed during the fatal attack.

Fibres expert Roy Green and his colleagues microscopically compared tiny fibres found on exhibits and used a machine to scientifically measure their colour.

The rarity of fibres was partly quantified by how often they occurred in a Home Office database compiled in the 1980s.

The team found a total of 16 fibres linked to Mr Lawrence's clothes on tapings - where sticky tape is passed over the garment - from Dobson's jacket and its original evidence bag.

These included four rare red-orange polyester fibres and seven quite common pink-orange fibres that matched Mr Lawrence's T-shirt - one of which appeared to be bloodstained. There were also two quite rare blue-green acrylic fibres which matched Mr Lawrence's jacket.

In debris from the original packaging of Dobson's jacket there was one red-orange fibre matching Mr Lawrence's T-shirt and a fragment of blood that contained two quite rare blue acrylic fibres that matched his cardigan.

Seven fibres were found on tapings from a sweatshirt seized from David Norris' house - six from Mr Lawrence's trousers and one from his T-shirt.

Hairs specialist Deborah Hopwood told the court that a number of short, cut fragments of hair were found on sticky tape passed over Mr Lawrence's outer clothes.

The team then discovered two tiny hairs among debris recovered from the Norris jeans - one of which was 1mm long and appeared to be bloodstained at one end. It was too small to send for DNA analysis.

The other was 2mm long and was sent to the United States to be tested for mitochondrial DNA. This is a short DNA sequence inherited from the mother and shared with anyone in the maternal line of a family.

The hair had the correct profile for the maternal line of Mr Lawrence's family. It could not be tested for nuclear DNA because the hair had no root.

Threads: A pair of green cord trousers worn by Mr Lawrence

An LGC forensic examiner's notes of exhibit LH5, a jacket found at Gary Dobson's address

Bags of evidence: Seals of all key exhibit items that was shown to the jury in the trial

Steve Allen, Managing Director of LGC Forensics said: ‘I'm extremely proud of the work that LGC's forensic scientists did on this case. Persistence, meticulous science and innovation can help convict criminals years after they committed the crime.

‘This case shows that the key to successful forensics is to assume nothing - which is all the more important in historic cases like the murder of Stephen Lawrence.’